remove nav. from the pool remove the leading hose which is a special hose not like the rest of the hoses and hold it by the neck, drain all the water and turn the machine by hand, slowly, you should hear gears moving smooth if is rough or if it skips teeth then your gear box needs replacing, if you take the nav. apart you will see a square plastic box in the upper portion of the housing, the funtion of this box is to send water thru the inlet when the robot gets stuck after a short time making the top gears move which are connected to the neck where the leading hose is attached making it turn. Now, all this checks should be done if you have enough pressure going thru the hoses. Also check your hoses to make sure there are no clogs and check under the nav to make sure the inlet is not clog with debris, if you have enough press and no clogs the continue with the removal of the navigator from your pool.